134 



MASSES OF CHALK IN DKIFT. 



[Ch. XL 



are so complicated that not only may we sometimes find portions of 

 them which maintain their verticality to a height of 10 or 15 feet, but 

 they have also been folded upon themselves in such a manner that con- 

 tinuous layers might be thrice pierced in one perpendicular boring. 



At some points there is an apparent folding of the beds round a cen 

 tral nucleus, as at a, fig 120, where the strata seem bent round a small 



Fig. J21 



Fig. 120. 



Folding of the strata between East 

 and West Run ton. 



Section of concentric beds west of Cromer. 



1. Blue clay. 3. Yellow Sand. 



2. White sand. 4. Striped loam and clay. 



5. Laminated blue clay. 



mass of chalk ; or, as in fig. 121, where the blue clay, No. 1, is in the 

 centre ; and where the other strata, 2, 3, 4, 5, are coiled round it ; the 

 entire mass being 20 feet in perpendicular height. This appearance of 

 concentric arrangement around a nucleus is, nevertheless, delusive, being 

 produced by the intersection of beds bent into a convex shape ; and that 

 which seems the nucleus being, in fact, the innermost bed of the series, 

 which has become partially visible by the removal of the protuberant 

 portions of the outer layers. 



To the north of Cromer are other fine illustrations of contorted drift 

 reposing on a floor of chalk horizontally stratified and having a level sur- 

 face. These phenomena, in themselves sufficiently difficult of explanation, 

 are rendered still more anomalous by the occasional inclosure in the drift 

 of huge fragments of chalk many yards in diameter. One striking in- 

 stance occurs west of Sherringham, where an enormous pinnacle of chalk, 

 between *70 and 80 feet in height, is flanked on both sides by vertical 

 layers of loam, clay, and gravel. (Fig. 122.) 



This chalky fragment is only one of many detached masses which have 

 been included in the drift, and forced along with it into their present 

 position. The level surface of the chalk in situ (d) may be traced for 

 miles along the coast, where it has escaped the violent movements to 

 which the incumbent drift has been exposed.* 



We are called upon, then, to explain how any force can have been 

 exerted against the upper masses, so as to produce movements in which 

 the subjacent strata have not participated. It may be answered that, if 



* For a full account of the drift of East Norfolk, see a paper by the author 

 Phil. Mag. No. 104, May, 1840. 



